CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Accumulated other comprehensive income	Accumulated deficit
Balance at beginning of period (shares) at Dec. 31, 2018		32,538,857
Balance at beginning of period at Dec. 31, 2018	$ 201,576	$ 33	$ 751,109	$ 9,479	$ (559,045)
Increase (Decrease) in Stockholders' Equity
Net loss for the period	(40,912)				(40,912)
Issuance of common stock, net of issuance costs (shares)		1,854,838
Issuance of common stock, net of issuance costs	107,883	$ 2	107,881
Share-based compensation expense	$ 11,131		11,131
Exercise of options for cash (shares)	235,398	235,398
Exercise of options for cash	$ 2,668		2,668
Net exercise of warrants (shares)	1,400,000	1,400,000
Net exercise of warrants	$ 0	$ 1	(1)
Proceeds from disgorgement of shareholders' short-swing profits	1,050		1,050
Unrealized gain (loss) on investments	158			158
Balance at end of period (shares) at Mar. 31, 2019		36,029,093
Balance at end of period at Mar. 31, 2019	$ 283,554	$ 36	873,838	9,637	(599,957)
Balance at beginning of period (shares) at Dec. 31, 2019	39,517,329	39,517,329
Balance at beginning of period at Dec. 31, 2019	$ 382,295	$ 40	1,144,667	9,889	(772,301)
Increase (Decrease) in Stockholders' Equity
Net loss for the period	(86,655)				(86,655)
Issuance of common stock, net of issuance costs (shares)		3,538,462
Issuance of common stock, net of issuance costs	323,977	$ 4	323,973
Share-based compensation expense	$ 21,567		21,567
Exercise of options for cash (shares)	496,521	496,521
Exercise of options for cash	$ 15,183		15,183
Proceeds from disgorgement of shareholders' short-swing profits	41		41
Unrealized gain (loss) on investments	$ (182)			(182)
Balance at end of period (shares) at Mar. 31, 2020	43,552,312	43,552,312
Balance at end of period at Mar. 31, 2020	$ 656,226	$ 44	$ 1,505,431	$ 9,707	$ (858,956)